Merger mania is keeping the market in positive territory so far, despite an early surge on Wall Street fizzling out.

Having jumped more than 100 points at the open - on the back of the financial help for US mortgage groups Freddie Mac and Fannie Mae, not to mention Anheuser Busch caving in to the $52bn (£26bn) InBev bid - the Dow Jones Industrial Average is now down around 4 points. Both Freddie and Fannie have lost their earlier gains, as investors took the view that the repercussions from the US housing slump were not over yet.

But with bid speculation surrounding ITV - up more than 11% now - and confirmed approaches for Kazakhmys, Alliance & Leicester and Imperial Energy, the FTSE 100 is 45.9 points higher at 5307.5 and the FTSE 250 is 104.8 points ahead at 8443.9.

Among the fallers, information group Thomson Reuters has declined another 43p to £12.42 after UBS moved from neutral to sell with a £12.60 target.